In the field of automobiles as representative vehicles, a so-called glass antenna, which is disposed as a print or sticker antenna on the surface of a window glass such as a front window, and receives radio wave (signal wave) outside the vehicle, has been proposed.
As an example of such glass antenna, preceding Japanese Patent Laid-Open No. 9-130124 by the present applicant and U.S. Pat. No. 6,008,767 as its corresponding U.S. application propose an antenna structure for a vehicle that disposes a reverse-convex-shaped antenna element (that is, the antenna element has convex shape in lower direction) on a front window to receive TV (television) radio wave.
According to the aforementioned prior arts, TV radio wave can be satisfactorily received in a vehicle on the move without any antenna element that protrudes outside the vehicle.
However, as general characteristics of an antenna element, since the optimal size and shape largely vary depending on the wavelength (frequency range) of radio wave to be received, a reverse-convex-shaped antenna element must have a considerably large size if it is used as that for receiving FM (frequency modulation) or AM (amplitude modulation) wave, and as such it disturbs the driver's sight on the front window.
When an antenna element is formed as a print antenna, if the pattern of the antenna element is partially disconnected for some reason (e.g., upon cleaning, exchanging an automobile inspection sticker, or the like), the reception characteristics of the antenna element considerably change from original reception characteristics. If an antenna element having a large size is used on the surface (the surface on the passenger room side) of a front window glass to satisfactorily receive FM or AM wave, troubles due to such pattern disconnection are highly likely to occur.